SPI1 and cancer: For example, the delivery of the transcription factors PU.1, IRF8, and BATF3 to cancer cells via replication-deficient adenovirus enables the direct reprogramming of cancer cells into dendritic cells.20 Compared with replication-deficient adenovirus vectors, OVs have the unique capability of selectively and directly delivering therapeutic payloads to cancer cells and increasing transgene copy number and expression efficiency via virus replication.